The present invention relates to a shift lever unit for transforming the movements of a shift lever in electrical controls signals. The invention relates in particular to a shift lever unit for the electrical control of a gearbox, preferably for the use in a motor vehicle.
In a motor vehicle the movements of a shift lever for changing the gears are typically mechanically transmitted to the gearbox of the vehicle. To this end, the tilting of the shift lever is in the shift lever unit transformed in longitudinal movements of several bowden cables or a linkage. The bowden cables or the linkage are connected to the gearbox and cause the changing of the gears.
This purely mechanical control, however, involves all disadvantages which arc related to the use of moving mechanical parts. For example, considerable maintenance work is necessary for the regular lubrication of the bowden cables or the bearings of the linkage. Further, the replacement of one of the mechanical components causes high costs, since at least parts of the shift lever unit and the gearbox as well as the bowden cables or the linkage have to be taken apart and subsequently put together again.
For avoiding these problems, it has therefore been considered to electrically control the gearbox of the vehicle, that is, electrical control signals operate mechanical actuating means at the gearbox which perform the desired shift of the gear. The electrical control allows further an electronic supervision of the shifting. Thus, shifting mistakes and the corresponding damages to the gearbox can be avoided.
In spite of these advantages, electrically controlled gearboxes have up to now not been accepted. This is in particularly due to the customers which have been used for decades to purely mechanical gear shifters. Typical operating means for electrical control signals, as for example push buttons or rotary switches etc., differ in their use fundamentally from the normal shifting unit of a purely mechanical shift control.
The DE 196 08 981 discloses a shift lever unit of considerable size and complexity, where the rotations of a shift lever around two axes cause a sliding movement of a control element arranged below the lower end of the shift lever. The control element comprises reflecting areas which are used by several sensors to detect the position of the control element and to transform the movements of the shift lever in electrical control signals for a gear box of a vehicle.
It is therefore the problem of the present invention to provide a compact and simple (and therefore not expensive) shift lever unit which reliably transforms the familiar movements of a shift lever into electrical signals for the control of a gearbox.
The invention relates to a shift lever unit for transforming the tilting movements of a shift lever in electrical control signals, in particular for the control of a gear box, with a shift lever, a rotating element which is rotated by the tilting movements of the shift lever and a sensor detecting the angular position of the rotating element and transforming it into electrical signals. The pattern of the movements of the shift lever (length of the movement, different tilting directions) corresponds exactly to the typical movements during shifting with a purely mechanical gear shifter so that it is not necessary to get used to operate the electrical shift lever unit. The rotating clement rotated by the shift lever during shifting assigns each shifting position an angular position. The sensor detects this angular position and provides a corresponding electrical output signal. Thus, the movements of the shift lever are in an unambiguous way transformed into electrical control signals for the gearbox.
Preferably, the rotating element is arranged above a suspension of the shift lever, so that a compact size of the shift lever unit is obtained. This further allows an easy access to the sensor in case a repair or a replacement is necessary.
According to a first preferred embodiment, the rotating element is a rotatably arranged disk and the shift lever extends through a slit in the disk so that a tilting of the shift lever causes a rotation of the disk.
According to a further preferred embodiment, the rotating element is a rotatably arranged hemisphere and the lever extends through a slit in the hemisphere so that a tilting of the shift lever causes a rotation of the hemisphere.
Preferably, the sensor comprises a contact element arranged on the rotating element and corresponding contact areas, electrically contacted by the contact element. According to a further preferred embodiment, the sensor comprises a magnetic contact, arranged on the rotating element and causing in at least one corresponding magnetic field sensor an electrical signal. The magnetic field sensor is preferably a Hall generator. According to yet another preferred embodiment, the sensor comprises a light source arranged on the rotating element and causing in at least one corresponding photo cell an electrical signal.
The rotating element comprises preferably on its circumference at least one notch which a spring engages to lock the rotating element in a predetermined angular position. The angular position corresponds preferably to a contact between the contact element and a contact area or the generation of an electric signal by the magnetic contact or the light source, respectively. The spring comprises preferably a roll at its upper end rolling along the circumference of the disk. These features provide the typical xe2x80x9clatch feelingxe2x80x9d as in case of a mechanical gear shifter, when a gear is selected.
Preferably, the shift lever unit according to the invention further comprises a blocking device which can block the rotations of the rotating element. The blocking may for example be used, if unallowed gear shifts (for example the unintended change into reverse) is to be avoided. A further possible use is the combination with the security system of the vehicle. To this end, the gearbox is blocked together with the application of an electronic immobilizer and/or a central locking unit of the car.
Further improvements of the invention are the subject matter of the dependent claims.